We have a free, donated account from rsync.net that lets us store 50GB of data
there.

We use duplicity (as per the rsync.net official document). We do full backups
weekly and incrementals daily. We encrypt these backups.

The only server essential to continued operation of the site is
linode.openhatch.org. The other servers do unimportant things that do not keep
state. It would be convenient to have backups for them, but it is not
essential, so for now I suggest we simply skip it.